1. Technical Field
The present invention relates to a universal serial bus (USB) hub for extending the number of peripheral devices connectable to a computer system, and more particularly, relates to an overcurrent protection circuit for a USB hub unit which is capable of preventing overcurrent from flowing to subsequent USB hub units and/or peripheral devices connected to the USB hub unit.
2. Related Art
Contemporary computer systems generally consist of a main unit (which may have built-in storage devices such as floppy disks, hard disks and CD-ROM), a keyboard and a monitor. The main unit may be connected to a display monitor and many other peripheral devices such as a keyboard, an input mouse, a digital still camera, a modem, a scanner, a telephone and a printer. However, standard computer systems support only a limited number of interface slots. Consequently, only a limited number of peripheral devices can be connected to the computer systems for operation. In addition, many peripheral devices have unique connectors that may not be interchangeable with the computer system, and must be carefully plugged into corresponding connectors of the interface slot of the computer system for operation.
In order to relieve cable congestion and reduce the number of connectors contained in the computer system, a universal serial bus (USB) hub has been proposed to serve as a central connection point of the computer system for power and data distribution to a wide variety of peripheral devices. Multiple sub universal serial bus (USB) hubs may be connected to a main universal serial bus (USB) hub for power and data distribution to as many peripheral devices as desired. While the USB hub permits the computer system to conveniently control power distribution over different peripheral devices. I have observed that there is no effective means to prevent overcurrent from flowing from power output ports of a main universal serial bus (USB) hub to secondary USB hubs and/or peripheral devices connected thereto.